The 40mm grenade launcher is probably the most popular 40mm attachment for the assault class. It opens up a lot of options for you, and acts as an excellent force multiplier. In terms of killing enemies, it allows the player to take down enemies hiding behind stone or concrete walls or inside buildings. Even if you don't kill him when you blow apart a corner of a building, more often than not you'll spook him out of hiding, allowing you and/or your teammates to finish the job. The only tricky part is aiming. The 40mm fires in a pretty severe arc, but once you have it down, you'll be able to lob grenades with frightening accuracy. The grenade does 100 damage out to 1.8 meters, going up to 125 when using Improved demolitions, allowing you to take down body armor users. The damage dissipates from there, going down to nothing at 5 meters.
Your 40mm grenade requires 0.2 seconds of flight time in order to arm the warhead. However, if your aim is good, you can kill people by direct impact if your close enough!
Indirectly, the 40mm grenade is excellent for opening up new avenues of approach for either assault or escape. Can't go down that road because a shielded HMG is covering it? No problem. Just fire this baby at a stone house, and voila! You've got a neat little mouse hole with which to flank your enemies. Just remember that mouse holes go both ways, and your enemies can use them just as well.
Fun Fact: It takes 32 direct hits from a 40mm GL to destroy an M-COM station.
Statistics
Fire Mode: Single shot Rate of Fire 1 round every 2.5 seconds Magazine Size: 1 Reload time: 2.45 seconds Damage Radius: 100 at apex out to 1.8 meters. Drops to zero at 5 meters. Ammo box Resupply time: 10.5 Seconds
As you can see, the sights provide a 'ladder' for helping you aim at long ranges. However, at most ranges your targets are going to fall within the first and second 'rungs'. Especially if you have the high ground.
Just an example of what 40mm GL rounds do to flimsy wooden structures.
Just remember, that you are very vulnerable when you have the 40mm out, because it takes time to swap back to your AR, and you have to have lady luck on your side if your hoping to kill an enemy via direct impact if they get too close. The best tactic is to pop out, fire your grenade, and get back behind cover. The 40mm makes a very distinctive noise, and makes a very noticeable telltale trail of smoke leading back to your position. Odds are, angry swarms of bullets are going to be coming your way soon after you let one fly.
If you like doing things the hard way, the 40mm GL does a mere 75 damage vs. vehicles, but sometimes can result in a lucky kill if the vehicle is very badly damaged.